Locked in cell-like rooms, with bars on the doors, this vast, soulless detention centre is no place for children. Yet at least 85 children were living there, some with their families, but others like Sarah, unaccompanied.

All of these children have painful stories of crossing the desert or the sea, of being torn apart from their families and of the desperate journey for a better life that refuses to come.

On that sunny winter day, through funding from the European Trust Fund, our group from UNICEF worked with the UN Refugee agency (UNHCR) to provide warm clothes to every one of the almost 100 infants and children in this center.

It felt good to bring a little bit of comfort and to see these children trying on new clothes with excitement.

But they need so much more. Basic hygiene and health care. And education, so that they don’t fall behind. Some children have stayed in such centers for years, without a single book to read or to learn from.

Together with the International Organization for Migration (IOM) and based on the best interest of each child, UNICEF is working to return these children home with dignity, to start the healing process after such distress.

If these children come from “countries of concern,” such as Syria, Somalia or Eritrea, however, returning them home is not an option. Instead, with the support of UNHCR, the aim is to find a country to host them as refugees. Italy, Germany and France are among the countries that have received some of these children, but more are needed. Last year, nine out of 10 children arriving in Italy by sea from Libya were unaccompanied.

UNICEF is also working with partners to find alternatives to detention for children. Discussions are already underway with one municipality in Tripoli to create such a safe haven.

Children should not be detained. Boys as young as 11 should not be treated in the same way as men, nor should they be separated from their mothers and siblings. We are advocating with the Libyan authorities to change this.

But, if they are detained, humanitarian imperative dictates we should still provide children in detention with the bare necessities for survival and a decent living, including recreation and educational activities, lest we forget that education and play are among the fundamental rights of every child. This is why we do it.

Ironically, these children in official detention centers are perhaps not the worst cases.

For every one of them, there are 30 more, not seen or counted, somewhere in the vast country that is Libya. It could be an adolescent girl or boy, unaccompanied or separated from their parents, who were cheated into believing they would be able to take their families to Europe.

Who knows the suffering or abuse one of these children might face?

We, at UNICEF, do all we can to find these invisible children.

We will help establish hotlines, strengthen coordination with authorities to trace and register children, widen our network of partners in remote areas, as well as with key sub-Saharan countries, and provide basic services on the migration route, in the hope that children on the move will be rescued.

We will do everything we can to restore their faith (and ours) in humanity.

For Makene and Sarah, the future is uncertain. Makene and her father will likely be repatriated to Cote d’Ivoire, but Sarah, now an orphan, needs a solution. UNICEF will work with other UN agencies to see if she can return to Guinea to live with extended family or help find other resettlement options if needed.

That winter day in Tarik al-Matar detention center, I smiled for Makene and Sarah as I held them in my arms, and kept my tears for when they looked away.